EP0042645B2

EP0042645B2 - Obstacle protection arrangement

Info

Publication number: EP0042645B2
Application number: EP81200664A
Authority: EP
Inventors: Theodorus Johannes Maria Van Schie
Original assignee: STAAT DER NEDERLANDEN te dezen vertegenwoordigd door de Directeur-Generaal van de Rijkswaterstaat
Current assignee: STAAT DER NEDERLANDEN te dezen vertegenwoordigd door de Directeur-Generaal van de Rijkswaterstaat
Priority date: 1980-06-24
Filing date: 1981-06-12
Publication date: 1988-12-28
Also published as: EP0042645A2; DE3161882D1; EP0042645A3; JPS606410B2; ATE5828T1; EP0042645B1; NL8003653A; US4399980A; JPS57133909A

Abstract

Obstacle protection arrangement composed of a series of interconnected deformable segments (A) each comprising a gate-shaped support member (G) and a box structure (N) containing ripple tubes (B), both sides of the arrangement being formed by overlapping flank members (C) such that during a front collision there will be dissipation of energy by deformation, whereas during a side collision the arrangement behaves like a rigid girder.

Description

The invention relates to an obstacle protection arrangement comprising a deformable spatial structure wherein a dissipation of energy is brought about during a deformation resulting from a collision with a moving object such as a road vehicle, which arrangement is composed of a series of segments which are interconnected - in the direction of motion as anticipated - and which are each comprised of at least one portal-shaped support member standing on the ground and positioned transversely to said direction, as well as of a stabilising structure fastened thereto and internally provided with deformation elements, a flank member being affixed on both sides of each segment. A specific object of such an arrangement as known from Dutch patent-application 7607171 (US-A 3 982 734) is to protect solitary obstacles by roadsides in such a manner that vehicles that have come off the roadway are prevented from coming into contact with such an obstacle. It occurs not infrequently that such solitary obstacles are located in the pointed area at exits or in the continuous shoulder along the roadway.
The protection of an obstacle may be achieved in two ways. In the event of a collision occurring on the nose portion of the obstacle protector means, the vehicle is to be stopped prior to touching the obstacle to be protected. If a collision occurs with the flank of the obstacle protector means, the protector means is to change the direction of travel of the vehicle and to guide it past the obstacle. In both such cases the occupants should not be exposed to intolerably high decelerations.
In practice obstacle protectors are known to exist which offer no or unsuitable flank protection. Also, several types of obstacle protection arrangements often require an elaborate foundation and anchoring. In addition, various types of obstacle protectors either do not function or do not function in an optimum fashion in the event of a head-on collision if the structure is V-shaped, for example when placed in a pointed area.
The object of the invention is to provide an improved arrangement which can be used in a V-form for a pointed area at an exit, but also in a parallel form in the shoulder along the roadway.
When starting from the above mentioned US-A 3 982 734 one notes that each flank member (called lateral buffer beam) in a first embodiment (Figs. 1-6) of said known obstacle protection arrangement is related to the support member (called base supports) by means of a pair of transversely extending, mainly triangular support plates (13,14,26,27). These latter plates are positioned firmly laterally and freely longitudinally by chains or cables anchored to the pavement or roadway. Between two spaced paires of plates a stabilizing structure (called container) internally comprising deformation elements, is provided. According to a second embodiment (Figs. 7-11) the support plates (53) are secured to the roadway as previously described and illustrated.
These latter plates are longitudinally related by the flank members. Between two adjacent plates a stabilizing structure (now called energy absorbing units) are disposed as previously described. It can only be understood that it are the flank members (buffer beams 54, 56) which keep the whole structure together. This leads to the conclusion that the stiffness in transverse direction (necessary for glancing impacts) is mainly obtained from the flank members and from the chains or cables.
The technical problem to be solved by the present invention consists in providing a sufficient lateral stiffness of the obstacle protection arrangement.
These objects are attained according to the invention by means of an arrangement in which - viewed in the direction of motion as anticipated - only the rear support member of the arrangement is fastened to a foundation, only the front support member being located in a horizontal guideway allowing displacement in the longitudinal direction only, and in that the segments are directly fixedly coupled to one another, so that the whole arrangement behaves like a rigid girder in respect of lateral impacts.
These measures lead to a construction of an obstacle protector means which affords a high degree of rigidity against bending both in a horizontal and in a vertical plane, so that two points of foundation are sufficient.
The obstacle protecting arrangement contains a core or backbone (the fixedly intercoupled segments) which is rigid towards bending forces originating from glancing impacts, but weak relative to a head-on collision. The arrangement as a whole can be installed or replaced by putting the front support member in the guideway and by securing the rear support member to a foundation.
An embodiment of the obstacle protection ar- rangment which facilitates the realisation of the rigid girder concept is defined in claim 2.
A most efficient solution for providing for an appropriate energy-absorbing capacity of the structure is obtained by providing each said structure with crumple tubes which absorb the major portion of the energy in a collison. If need be, it is possible to increase the deformation resistance of the successive segments - as viewed in the longitudinal direction - by using more crumple tubes.
In order that the crumple tubes may function without disturbances occurring, top and bottom sides of the stabilising structure which may comprise a box-like structure, are creased a little outwardly, at least one rod being disposed between these expanded areas. This form of construction is also favorable when transporting the individual box-like structures, and prevents damage due to vandalism. According to a particular embodiment, each segment is provided with flank members extending on both extremities past the respective segment so that there is an overlapping with neighboring flank members, in which case the connection of the adjoining segments is also carried through by means of at least one double-angled strip forming a connection with the support member, said strip affording a change in the mutual position on the one hand, but no substantial change in the angle of the flank extremities on the other.
It is important that upon impact the divergence of the flank members does not result in the occurrence of laterally directed spearheads formed by the extremities of the flank members. This danger is avoided if the flank members are provided with longitudinal undulations engaging one another at overlapping sections, an extra flange part forming a guide when the flanks slide past each other. This form of construction at the same time increases the rigidity of the obstacle protector arrangement in a vertical plane.
The invention will be further explained with reference to the drawing showing several diverse forms of the obstacle protector arrangement as well as details taken therefrom.

Fig. 1 is a top view of a diverging obstacle protector arrangement to be used for the protection of an obstacle in a pointed area.
Fig. 2 is a side view of the arrangement according to fig. 1.
Fig. 3 is a top view similar to fig. 1 of an obstacle protector arrangement having a parallel form as is to be used for the shoulder along a roadway.
Fig. 4 is a side view of the arrangement according to fig. 3.
Fig. 5 is a top view of an alternative form of the arrangement shown in figs. 1 and 2.
Fig. 6 shows, on an enlarged scale, a detail of the arrangement as per fig. 1.
Fig. 7 is a sectional view taken along line VII-VII in fig. 6.
Figs. 8A and B provide a perspective view and a front view, respectively, of a nose segment of the obstacle protector arrangement according to the invention.
Fig. 9 is a perspective view of the box-like structure of fig. 6 with edge faces being partially cut out.
Figs. 10-12 show a double-angled strip of the obstacle protector arrangement of the invention. The figs. 13 and 14 illustrate two situations arising in the event of a collision.
Fig. 15 shows a construction enabling to absorb occurent tensile forces into a flank member of the alternative form of embodiment as per fig. 5.
Figs. 16A + B + C provide three views of a nose segment.
Figs. 17A+B show the results of an excentric impact upon the nose segment.

As can be seen best in the figs. 1 and 3, the obstacle protector arrangement is comprised of a series of interconnected segments A provided with a nose segment A'. Each segment is composed of a portal-shaped support member G disposed transversely to the direction of motion X and provided for fastening an internal stabilising structure in the form of a box-like structure N. The support members G are slidably or rollably supported on the ground, with the exception of the rear portion which is attached to a fixed foundation L. Also, to said foundation L there are attached tie members which are to absorb the longitudinal forces occurring in the associated guide rail construction. The nose segment A' is provided with a guide member H which prevents displacement in any direction other than the direction of travel X (see figs. 8A and B).
Each segment is provided on both sides with a flank member C which is connected to the associated support member G via an angled strip D. The shape and function of these strips D are illustrated in the figs. 10-12. On the bending lines of the strip it is possible to provide weakened sections, for instance bore holes. These strips afford a displacement of successive flank members past one another. The support members G move along, thus causing a certain degree of transversely directed deflection to occur so that tings do not get stuck. The flank members will not deflect sidewardly, which is also in the interest of preventing damage to vehicles of third parties or injury to the latter.
Fig. 9 clearly shows that each box-like structure N is provided with crumple tubes B. The purpose of these tubes is to absorb the major portion of the kinetic energy of the colliding vehicle. In addition, the box-like structure N imparts stability to the entire structure, specifically at the occurrence of lateral forces (see figs. 13 and 14). The boxlike structure facilitates transport and assembly of the obstacle protector arrangement.
The construction of the nose segment A' is best apparent from the figs. 8A + B and 16A + B + C. There is an arcuate nose apron C' which may be regarded as a complement to the flank members C ending in said segment. The support member G' cooperates on its lower side with a foundation guide member H. Inside the nose apron C' there are provided several straight thin plates U (see figs. 16A + B + C). This enables the nose segment at the beginning of the collision to adopt the shape and/or deformation of the vehicle in a manner so that the deformative force of the nose segment is lower than the threshold value of the crumple tubes. This causes the deforming of the first box-like structure to be introduced in a proper manner (figs. 17A + B).
The functioning of the obstacle protector arrangement is dependent upon the manner in which the collision with the structure proceeds. In a collision a distinction may be made between a head-on collision and a lateral collision. A head-on collision may be still further differentiated into a centric, an excentric and an angular collision. In the event of centric collision, first the nose apron of the structure will deform. Thereupon, the support member G' will start sliding freely with its feet in the foundation guide member H, and the two flank members C will be pushed backwards. Simultaneously, the first box-like structure will be compressed. The subsequent segments A will be compressed in succession. The number thereof depends upon the magnitude of the quantity of kinetic energy to be destroyed.
The deceleration of the vehicle is determined by:

a) Crumple resistance of the crumple tubes (B).
(b The acceleration of masses (segments A and A' and flank members C).
c) Several other resistance factors such as: deforming resistance of the nose segment A' mutual friction of the flank members C rolling and slid
ing resistance of the support members G resistance factors of the vehicle itself.

Due to the influence of the mass intertia and occurrent frictions in the structure, the segments will deform one by one. The box-like structure N is so designed that the upper plate can feely bend upwards and the lower plate can freely bend downwards (see fig. 9). Such upward and downward bending quality is important so as to prevent the tubes from being struck by the lower or upper plate during impact. In order to ensure this shape, the box N is internally provided with spacer means S. The lower and upper plates can absorb tensile forces in the event of a lateral collision. The spacer means S are also advantageous in preventing damage due to vandalism committed by passers-by (tourists) climbing upon the obstacle protector arrangement. The crumple tubes B in the box N are centered and fixedly secured on the frontal face by means of the spiders M. On the back side they are confined in holes provided in the back plate of the box. By pre- mounting the crumple tubes, errors are avoided when assembling the structure.
The support members G are so designed as to afford easy and safe mounting of the boxes N through bolt holes on the upper and lower sides, see fig. 9. The wheels on the legs of the support members G ensure a smooth displacement of the support members in the longitudinal direction of the structure.
The flank members C have a length of more than twice the length of one segment. They overlap each other, with on the back side a guide retainer E (see fig. 7) over the next flank member. The flank members can slide passing one another without there being the danger of a secondary collision of the guide retainer E with the flank member of the second segment following, because they have already passed one another on the original position. The advantage of a great lenght of overlapping is that it increases the lateral and vertical stability of the whole structure.
The flank members C are connected to the support members G by means of angled strips D (figs. 10-12). The strips D afford the flank members a certain amount of movability with respect to the support member(s) G. This is necessary because in the event of a head-on collision and the successive telescoping of segments:

a. The angle formed by the flank members with respect to the support members may change.
b. The distance of the flank members to the support members may change.
c. The flank members must obtain some freedom so as to reduce the influence of mass inertia on the forces in the structure and on the deceleration of the vehicle.
In addition, in the event of a lateral collision.
d. The strips provide an extra braking path and the flank members undergo a smooth deformation.

As a result of the form of the angled strips the movements in the horizontal plane as described can be realized while ensuring sufficient rigidity in the vertical direction. A proper vertical position of the support members G is a condition for the intended behavior of the boxlike structure N.
Excentric head-on collisions are understood to be those collisions in which the longitudinal axis of the vehicle runs parallel to but spaced from the longitudinal axis of the stucture. In an angular head-on collision the longitudinal axis of the vehicle forms an angle with the longitudinal axis of the structure.
If the vehicle strikes the obstacle protector arrangement excentrically or at an angle, the nose apron A' is intended to be deformed in such a way that the vehicle is not thrown back. To this end the nose apron is provided with straight thin plates U (figs. 1 and 8). Relative to their points of fastening said plates are capable of absorbing tension but no pressure. As a result, the nose segment will be inclined to hold the vehicle. (See figs. 17A + B).
If, in an excentric or angular collision, the displacement in longitudinal direction is so large that the support member G' leaves the foundation guide member H, the whole obstacle protector structure is to be regarded as a projecting girder with respect to the supporting foundation L (see fig. 13). The box-like structure N can absorb this couple.
Another type of collision is the lateral collision. These collisions concern impacts of collision upon the flank of the obstacle protector means. In such an event the whole obstacle protector arrangement forms a beam having as points of support the ground rail H and the supporting foundation L. The upper and lower plates of the box N act, in the tension zone, as tension absorbers. The crumple tubes B act, in the pressure zone, as pressure absorbers (see fig. 14). The foregoing describes the obstacle protector arrangement having the box-like structure. This box-like structure is an essential element for increasing the stability of the structure. An alternative form of stabilising structure for obtaining the stability is attained by replacing the box-like structure by two crossed tension rod members F. (see fig. 5). This alternative embodiment essentially functions in a manner identical with that of the form of embodiment having the box-like structure. This form of construction with tension rod members likewise can be realized in a V-form and a parallel form.
The construction of the segments of this alternative embodiment is as follows. Between the support members G there are provided individual tubes B, whereupon parallel adjustment is effected by means of the tension rod members F. In the event of a lateral collision the compressive forces are again absorbed by the tubes B. Tensile forces are absorbed by the tension rod members F and the flank members C. For this purpose the flank members have been internally provided with tension absorbers J (fig. 15). For the purpose of increasing the stability the crossed tension rod members may be connected together in the center.

Claims

1. Arrangement for protecting an obstacle, the arrangement comprising a deformable spatial structure wherein a dissipation of energy is brought about during a deformation resulting from a collision with a moving object such as a road vehicle, which arrangement is composed of a series of segments (A) which are interconnected - in the direction of motion as anticipated - and which are each comprised of at least one portal-shaped support member (G) standing on the ground and positioned transversely to said direction, as well as of a stabilising structure (N, F) fastened thereto and provided with deformation elements (B), a flank member (C) being affixed on both sides of each segment, characterized in that, viewed in the direction of motion as anticipated - only the rear support member (G) of the arrangement is fastened to a foundation (L) only the front support member (G') being disposed in a horizontal guideway (H) allowing displacement in the longitudinal direction only, and in that the segments (A) are directly fixedly coupled to one another so that the whole arrangement behaves like a rigid girder, in respect of lateral impacts.

2. Arrangement according to claim 1, characterized in that each stabilising structure comprises a box-like structure (N) and on its frontal face each box (N) is affixed to the associated support member (G) of the segment (A) and is provided on its back face with two horizontal flange parts having holes cooperating with the holes in the support member of the adjoining segment, through which fastening bolts have been fitted.

3. Arrangement according to claim 1 or 2, characterized in that the deformation elements comprise crumple tubes (B) which absorb the major portion of the energy in a collision, and in that, if required, the deformation resistance of the successive segments - as viewed in the direction of motion as anticipated - increases by providing additional crumple tubes.

4. Arrangement according to claim 2 or claim 3, characterized in that, the upper and lower sides of the box-like structure (N) are creased a little outwardly, at least one rod (S) being disposed between these expanded areas.

5. Arrangement according to any one of the preceding claims, characterized in that, each segment (A) is provided with flank members (C) extending at both extremities beyond the segment concerned, so that there is an overlapping with neighboring flank members, and in that the connection of the overlapping extremities of the flank members (C) with the adjoining segments (A) is also realized by means of at least one double-angled strip (D) forming a connection with the support member (G), said strip affording a change in the mutual position, but no substantial change in the angle of the flank member, an extra flange part (E) forming a guide when the flank members slide past each other.

6. Arrangement according to any one of the preceding claims, characterized in that the frontal segment (A_') is provided with a plate bent about the front and forming a nose apron (C') several strips (U) in crosswise arrangement being secured behind said apron.